Efeitos da estimulação transcraniana por corrente contínua sobre a aprendizagem motora de indivíduos jovens

Abstract

Motor learning is the process by which the motor behaviors are modified by experience. Such process implies structural and functional in neural networks related to the trained task. The performance improvement associated with the training is a behavioral measure of learning, as well as the generalization and transference of the new ability to non trained segments. The transcranial direct current stimulation (tDCS) is a brain activity modulation technique that modifies the cortical excitability, causing changes in motor evoked potentials which may influence the motor learning process. Changes similar to long term potentiation have already been described, essential for the learning processes, after tDCS application. The primary motor cortex has been presented as the stimulation aim with the most positive effects on the motor learning process. OBJECTIVE: to investigate the effects of one-sided applied anode tDCS to primary motor area concomitantly with the train over learning, generalization and intermanual transfer of sequential finger movements, in young adults. METHODS: 40 young right handed adults with no motor or cognitive disabilities took part in the study, randomly divided into an experimental group (EG) and a placebo group (PG). EG executed the motor training of a finger sequence task simultaneously with anode tDCS applied on the primary motor cortex contralateral to trained hand. PG executed the same training simultaneously with simulated stimulation. The training consisted of 8 blocks with 300 repetitions of finger sequence movements performed only with the right upper limb. Performance was measured by sequential movements' speed and accuracy, taken before training, immediately after training, 48h after, 7 and 28 days after training considering trained hand (TH) for short and long term learning assessment. Additionally, performance assessments were done (1) in non trained sequence, named control sequence (CS) in TH for investigation on generalization; (2) in trained sequence (TS) in non trained hand (NTH), for investigation of intermanual transference. Statistical analysis was carried out using ANOVA variance test for performance over correct sequences within 1 minute considering groups (EG and PG) and assessments (BT, AT, 48hAT, 7dAT and 28dAT) as factors for short and long term learning investigation; groups (EG and PG), assessments (BT, AT, 48hAT, 7dAT and 28dAT) and sequence (TS and CS) for generalization investigation; and groups (EG and PG), assessments (BT, AT, 48hAT, 7dAT and 28dAT) and hand (TH and NTH) for intermanual transference investigation. RESULTS: For short and long term learning, results showed assessment effect, with no group effect. For generalization, results showed sequence and assessment effects, presenting that the trained sequence learning was partially transferred to the control sequence, with no group effect. Finally, for the intermanual transference, results showed hand and assessment effects, presenting that the gains with the trained hand training were also partially transfer...